One of the characteristics of the space environment is the micro-gravity that influences the human physiology but also the activity of the human acting in this environment. Since every object, also the human, is “floating” around in a space station, some objects might become projectiles and the performance of human might be reduced (i.e. lack of precision). It might end as a safety issue.
In the past different concepts have been designed and tested as the “triangle shoes” or the handrails but there are still some improvements to be done.
Two other concepts have been tested in ESA: one is based on the velcro concept but using a stronger material(polymer velcro), the other one being a tie down device fixed to rails on the floor.
Those systems were trying to fullfill the walking requirements and at this stage of development shall still be improved before judging definitively their efficiency.
The major difficulty with restraints being that their characteristics depend on the type of task to be performed but on the other hand a unique type of foot restraints shall be proposed to be used in a space station for technical and practical reasons.